Carotenoids include hydrocarbons (carotenes) and their oxygenated, alcoholic, derivatives (xanthophylls). Representative examples of carotenes include beta-carotene, alpha-carotene, and lycopene. Representative examples of xanthophylls include lutein, zeaxanthin, capsorubin, capsanthin, astaxanthin, and canthaxanthin. Carotenoids are abundant in fruits and vegetables and have been studied extensively as antioxidants for the prevention of cancer and other human diseases. Among the dietary carotenoids, the focus has been on beta-carotene that has been established to play an important role in the prevention of various types of cancer.
More recent research has shown that other carotenoids, particularly the xanthophylls, posses strong antioxidant capabilities and may be useful in the prevention of diseases including cancer. For example, it has been reported that the consumption of lutein and zeaxanthin leads to a 40 percent reduction in age-related macular degeneration (Seddon et al., 1994, J. Amer. Med. Assoc. 272 (18): 1413-1420). It has also been reported that an increased level of serum carotenoids other than beta-carotene is associated with a lower incidence of heart disease (Morris et al., 1994, J. Amer. Med. Assoc. 272 (18): 1439-1441). The xanthophylls, because of their yellow to red coloration and natural occurrence in human foods, also find uses as food colorants. Thus there is an increasing need for substantially pure xanthophylls, which can be used as nutritional supplements and food additives.
Although present in many plant tissues, carotenoids free of other plant pigments are most readily obtained from flowers (marigold), fruits (berries) and root tissue (carrots and yellow potatoes). Xanthophylls are typically present in plant chromoplasts as long chain fatty esters, typically diesters, of acids such as palmitic and myristic acids.
Although chemical processes for the synthesis of xanthophylls from commercially available starting materials are known, such processes are extremely time-consuming, involve multiple steps, and have not provided an economical process for the production of xanthophylls. A more economical route for the large-scale production of substantially pure xanthophylls is a process that extracts, isolates and purifies xanthophylls from natural sources. However, previous methods that isolate xanthophylls from natural plants suffer from one or more disadvantages. Specifically, previous methods are not suitable for commercial or industrial scale (e.g., about 10,000 lbs of green plants, or more); they do not provide at least about 0.25 kg of lutein and zeaxanthin substantially free (e.g., less than about 25 wt. %) of the lipids/fatty acids; they do not provide xanthophylls suitable for human consumption; they employ solvents and/or reagents that are relatively expensive, as well as relatively unsafe for the environment; they employ relatively large amounts of water; and/or they are carried out employing plants that are not an abundant renewable resource/perennial crop that require relatively low amounts of water, herbicides, pesticides, and fertilizer.
There is a need for a process for obtaining lutein and zeaxanthin (active metabolite of lutein) from green plants, suitable for commercial or industrial scale (e.g., about 10,000 lbs of green plants, or more). The process should provide at least about 0.25 kg of lutein and zeaxanthin substantially free (e.g., less than about 25 wt. %) of the lipids/fatty acids. As such, the lutein and zeaxanthin obtained will preferably include at least about 80 wt. % xanthophylls, suitable for human consumption. The process will preferably employ solvents and reagents that are relatively inexpensive, as well as relatively safe for the environment. The methods will preferably employ relatively low amounts of water. The methods can preferably be carried out employing a plant that is an abundant renewable resource/perennial crop that requires relatively low amounts of water, herbicides, pesticides, and fertilizer.